In known devices, such as the one described in French Pat. No. 2,231,221 filed on 23rd May 1973, for a sheet dispenser machine for dispensing sheets one by one, there is a component called a pile height sensor which is constituted by a small thin resilient blade which rests on the front part of the top sheet of the pile and exerts a light pressure thereon by its natural spring effect. When the level of the pile is lowered by the removal of a few sheets, this pile height sensor actuates a contact which starts a motor to raise the level of the pile of sheets.
However, with such a device, it is not possible to adjust the pressure exerted by the sheet feeder blade on the pile. This pressure may be considered as a constant pressure because of the small number of sheets removed between two starts of the motor for raising the level of the pile. Now, the pressure of the sheet feeder blade is a very important parameter for the proper operation of a dispenser and this pressure must be adjustable as a function of the physical characteristics of the sheets to be removed.
The present invention aims to produce a pile height sensor for exerting an easily adjustable pressure at the top of the pile of sheets to be removed.